Hard alloy



Patented Feb. 27, 1940 UNITED STATES PATENT OFFICE HARD ALLOY poration of New York Application May 2'1, 1936,

No Drawing.

Serial No. 82,044

10 Claims.

This invention relates to hard compositions of matter or alloys and has for a general object the production and provision of a novel and an improved composition or alloy which is resistant to abrasion or wear, corrosion, and combined wear and corrosion, and which, among other uses, may be employed in wear and corrosion resisting parts, dies and tools, for example, for turning or otherwise cutting metals.

Cast alloys suitable for tool materials have hitherto been classified as high speed steels, and non-ferrous alloys. Usually such alloys consist of a cobalt base, a metal of the sixth group of the periodic chart of the elements, and carbon.

Another object of the invention is to secure for a. cast composition or alloy of that general class, a marked resistance to cratering; that is, the wearing away of tool material adjacent a working edge of a tool made of the alloy. Such cratering is particularly objectionable in such tools as milling cutters, where the grinding of the tool is done on an edge thereof and is exceedingly difficult to do on the face of the tool.

Tantalum carbide is known to have an extremely high melting temperature. It is an object of the present invention to provide an alloy of the high speed steel class with an appreciable amount of tantalum carbide, which can be made by casting.

A further object of the invention is the provision of an alloy or composition made by casting a molten mixture of a plurality of hard refractory metals from the fourth, fifth, and sixth groups of the periodic chart of the elements and/or the carbides thereof, and cobalt.

Other objects and advantages of our invention will appear more fully from the following description.

Illustrative of the invention, an alloy or a composition adapted to accomplish the foregoing objects has been made from the following elements in the indicated percentages by weight:

To avoid the inconvenience of here reciting every specific variation which has been found to produce an alloy or product adapted to accomplish the objects of the invention, we are disclosing the following ranges of percentages which have been found to produce useful alloys or compositions in accordance with the invention:

Per cent by weight Coha It 30 to 60 Chromium 5 to 30 Tim g ten 15 to 50 Tantalum 15 to 50 Carbon 1 to 3 The invention is not limited to the specific elements mentioned above, but instead contemplates the .use of from 30% to 60% by weight of one or more metals of the iron group including not only cobalt but also iron and nickel, the remainder of the alloy being a plurality of hard refractory metals from the fourth and/or fifth, and sixth groups of the periodic chart of the elements, and carbon or another metalloid such as silicon or boron.

In the foregoing examples, the carbon has been stated in terms of percentages byrweight of all the alloy elements. It is probable that some, if not a major portion, of the carbon is in combination.

with'the tantalum and the tungsten for the reason that both tantalum and tungsten are known to have a great aifinity for carbon and for the further reason that the carbon is introduced in the alloy in the form of carbides of tungsten and/or tantalum. We do not, therefore, wish to limit our invention to the precise metallurgical structure of the alloy with reference to the allocation of the carbon. Instead, it should be understood that we contemplate the use of from 15% to 50% by weight of one or more tungsten group metals and/or their carbides, and from 15% to 50% by weight of one or more tantalum group metals and/or their carbides.

We have found, for example, that the tantalum and/or the tantalum carbide may be entirely or partially replaced by its molecular or volumetric equivalent of columbium from the tantalum or fifth group of the periodic chart of the elements and/or a carbide thereof, respectively, or by its molecular or volumetric equivalent of titanium or zirconium from the fourth group of the periodic chart of the elements and/or the carbides thereof, respectively. The tungsten and/or the tungsten carbidemaybe wholly or partiallyreplaced by its molecular or volumetric equivalent of molybdenum from the sixth r p of the periodic chart of the elements and/or a carbide thereof, respectively, in the alloy of the invention.

To. illustrate such replacemmts and the introduction of carbon in the manner already described, some of the tantalum carbide in the first example shown hereina'bove may be and has been partially replaced by the molecular equivalent of, coiumbium carbide to give an alloy having the following percentages by weight of the indicated ingredients or constituents:

group metal and the one or more metals of the iron group. When the fusion of the foregoing constituents is complete, the alloy is cast by pouring it into suitable molds. Y

when the alloy of the invention is made as disclosed above, it may be employed as, for example,atool,andsuchatoolwilltakeagood cutting edge when it is ground. The novel tool somadehasastrength asgood orbetter than the non-ferrous cutting materials hereinabove refrredtmhasahardnessin excessof that of commercial high speed steel, and is remarkably free from cratering when used in turning or otherwise cutting steel. To illustrate we cite the following examples:

carbides Hardness Breaking Example 00 M L W0 Cr Mo Rockwell strength 0 A scale kilograms Par uni Per out Per cent Per on! 22.6 15 83.8 852 19 3. 5 l6 88 1400 i. 7 ll. 4 10. 4 so. 1 1631 Columbium carbide 3.82

Thus it will be seenthat the molecular equivalent by weight of some of the tantalum carbide wise, some or all of the tantalum carbide and the tungsten carbide may be replaced by the molecular equivalents by weight of the above mentioned refractory metal carbides. In order, however, to avoid a long recitation of specific examples illustrating such variations in constituents within the purview of the invention, we are disclosing below the molecular equivalents in terms of percentages by weight of the various metals disclosed above, as replacements for tantalum and that disclosed as a replacement for tungsten, which correspond to the ranges of tungsten and tantalum, respectively, as already disclosed:

From 15% to 50% by weight of tantalum is the molecular equivalent of:

From 7.69% to 25.68% of columbium by weight;

From 3.98% to 13.29% of titanium by weight;

From 7.52% to 25.12% of zirconium by weight.

From 15% to 50% by weight of tungsten is the molecular equivalent of from 7.83% to 26.25% of molybdenum by weight.

when the novel alloy is made with any of the replacements just disclosed above, the percentages of the other ingredients are varied substantially in accordance with the respective amounts of the replacements within the ranges shown above, it being our intention to keep the amounts of the carbides of the fifth and/or fourth groups,

within the weight percentages shown above, constant by volume.

In producing the alloy of the invention as described above, the cobalt, or one or more metals ExamplesAandBusedasaturningtool cut the full length of a 31 inch long log of 1020 steel at a surface speed of 445 feet per minute, taking 0.016 inch depth of cut with a feed of 0.010 inch without showing any evidence of failure, or change in theappearance of the log. Under the same conditions, but using commercial tools of known non-ferrous alloys, the commercial tools exhibited intermittent brightening or glazing after a cutting distance of 19 inches.

The foregoing examples have also been subjected to uses involving wear and the corrosive action of hydrochloric and sulphuric acids and have shown marked superiority over other nonferrous or high speed steel alloys. In one such use, the alloy composition C above, as a refrigerator shaft bearing where it was subjected to hydrochloric acid formed from the organic chloride used as the refrigerant showed clearly the suitability of our novel alloy for uses wherein combined wear and corrosion are seriously limiting factors in the use of known alloys.

Attention has already been directed to the desirability of a tool material for use in the manufacture of the blades of milling cutters and similar tools where the grinding can be done only on the edge of the tool, and where cratering of the tool becomes a very serious objection. Tests of our novel alloy on cast iron indicate that it is as good or better than non-ferrous alloys in use, but that when turning steel it is much better than such non-ferrous alloys. It has a greater resistance to the heat developed in the tool with theresultthathigherspeedscanbeusedin turning steelthancanbeusedwith high speed steel tools or tools of other non-ferrous-alloys. Moreover, with the foregoing compositions, the melting temperature of our novel alloy is sumciently low to facilitate melting and casting the same, and yet the alloy is remarkably hard, strong, and tough.

Having thus described our invention in its present preferred form, we wish it expressly understood that it is not limited to the precise percentages and constitutents specifically mentioned above, but that it is capable of changes within the scope of the appended claims. Where in the following claims we use the term tungsten group metal" we mean one or more metals from the b-ll. 14-1 of and molybdenum.

What we therefore desire to claim and to secure by United States Letters Patent, is:

1. A hard alloy composition comprising from 30% to 60% by weight of one or more metals of the iron group; from to 30% by weight of chromium; a metal from the group composed of tungsten and molybdenum in an amount equal to the molecular equivalent by weight of from to 50% by weight of tungsten; one or more metals from the groups composed of tantalum and columbium, and titanium and zirconium in an amount equal to the molecular equivalent by weight of from 15% to 50% by weight of tantalum; and from 1% to 3% by weight of carbon.

2. A cast alloy composition comprising from to by weight of one or more metals of the iron group; from about 11% to 30% by weight of chromium; one or more metals from the group composed of tungsten and molybdenum in an amount equal to the molecular equivalent by weight of from 15% to 50% by weight of tungsten; a metal from the groups composed of tantalum and columbium, and titanium and zirconium in an amount equal to the molecular equivalent by weight of from 15% to 50% by weight of tantalum; and from 1% to 3% by weight of carbons 3. A cast alloy made from the following ingredients: from 30% to by weight of one or more metals of the iron group; from 5% to 30% by weight of chromium; one or more carbides of tungsten group metal in an amount equal to the molecular equivalent by weight of from 15% to 50% by weight of tungsten carbide; and one or more carbides of refractory fourth and fifth group metal in an amount equal to the molecular equivalent by weight of from 15% to 50% by weight of tantalum carbide.

4. A cast alloy made from the following ingredients: from 30% to 60% by weight of one or more metals of the iron group; from 5% to 30% by weight of chromium; one or more tungsten group metals in an amount equal to the molecular equivalent by weight of from 15 to 50% by weight of tungsten; and one or more carbides of refractory fourth and fifth group metal in an amount equal to the molecular equivalent by weight of from 15% to 50% by weight of tantalum carbide, a substantial portion of the tungsten group metal being in the form of carbide.

5. A cast alloy comprising from 30% to 60% by weight of one or more metals of the iron group, the remainder of the alloy being composed of from 5% to 30% by weight of chromium, and a carbide of a refractory metal from each of groups 4, 5 and 6 of the periodic chart of the elements.

6. A cast alloy comprising from 30% to 60% by weight of one or more metals of the iron group, the remainder of the alloy being composed of from 5% to 30% by weight of chromium, from 30% to 50% by weight of a. metal from the group composed of tungsten and molybdenum, and a carbide of a refractory metal of the fourth group of the periodic chart of the elements, a substantial portion of the tungsten group metal being in the form of carbide.

7. An alloy comprising from 30% to 60% by weight of one or more metals of the iron group, principally cobalt, the remainder of the alloy being composed substantially of from 5% to 30% by weight of chromium, from 30% to 50% by weight of the metal from the group composed of tungsten and molybdenum, and a carbide of a refractory metal of the fourth group of the periodic chart of the elements, principally titanium.

8. An alloy comprising from 30% to 60% by weight of one ore more metals of the iron group, principally cobalt, the remainder of the alloy being composed substantially of from 5% to 30% by weight of chromium, from 30% to 50% by weight of the metal from the group composed of tungsten and molybdenum, and a carbide of a refractory metal of the fourth group of the periodic chart of the elements, principally zirconium.

9. A cast alloy comprising from 30% to 60% by weight of one or more metals of the iron group, from 5% to 30% by weight of chromium, and at least one carbide of a refractory metal from each of groups four, five and six, of the periodic chart of the elements.

10. An alloy consisting of 50% tungsten, 2 to 3% carbon, 4 to 6% titanium, 10 to 15% chromium, and the remainder metal of the iron group.

CLARENCE W. BALKE. FREDERICK L. HUNTER, Jn. ROY A. HASKELL. 

